The present invention relates to a golf ball characterized by outstanding flying performance and shot feeling, which has a cover with improved scuff resistance and a coating film with improved wear resistance.
Many attempts have so far been made to prepare the cover of golf balls from a thermosetting polyurethane elastomer which is comparatively inexpensive and provides good shot feeling and scuff resistance. They are directed to improvement in shot feeling, controllability, and initial velocity (rebound resilience).
For example, Japanese Patent Laid-open No. Hei 9-215778 discloses a two-piece golf ball consisting of a rubber-based core having a specific gravity no lower than 1.00 and a cover having a specific gravity higher than that of the core. This golf ball has a moment of inertia which is adequately selected according to the hardness of the cover. Moreover, it has dimples with a prescribed area relative to its surface area, and its core and cover have an optimized hardness. With its cover formed from a thermoplastic polyurethane elastomer, it is improved in characteristic properties, such as flying distance, controllability, rollability and straight rolling on the putting green, rebound resilience, and durability on the cover by an iron shot.
Also, Japanese Patent Laid-open No. Hei 9-271538 discloses a golf ball consisting of a core and a cover, in which the cover is formed mainly from a thermoplastic polyurethane elastomer (based on an aliphatic diisocyanate) having adequate viscoelastic properties. This golf ball is claimed to be superior in controllability, initial velocity (rebound resilience), scuff resistance caused by iron shot, discoloration, and moldability.
Moreover, Japanese Patent Laid-open No. Hei 11-178949 discloses a solid golf ball having a cover formed mainly from a reaction product of a thermoplastic polyurethane elastomer and an isocyanate compound. It claims that this golf ball has improved moldability, shot feeling, controllability, initial velocity (rebound resilience and flying distance), and scuff resistance caused by iron shot.
Existing golf balls still have room for further improvement in shot feeling and flying performance. The new golf ball to be developed should exhibit improved flying performance and soft shot feeling and have improved scuff resistance for its cover and improved wear resistance for its coating film.